Field of the Invention
The present invention relates to an expander.
Description of the Related Art
A power generation apparatus disclosed in Japanese Patent No. 4684882 includes an expander, a generator, and a cooling medium pump which are disposed in order from the downside toward the upside and are integrated with one another.
The expander includes a rotary scroll that is rotated by the expansion of a vapor cooling medium flowing into a working chamber. The generator includes a motor shaft that is connected to the rotary scroll through a shaft and a rotor that is attached to the motor shaft. In the generator, power is generated by the rotation of the motor shaft and the rotor using the rotational movement of the rotary scroll transmitted through the shaft. A bearing that supports the motor shaft is provided inside a housing of the generator.
A vapor cooling medium including lubricant is introduced into the working chamber. The vapor cooling medium that has been used to rotate the rotary scroll flows to the upper portion of the generator through a discharge gas passage formed in the housing of the generator, and flows into the housing. At this time, the flow velocity of the vapor cooling medium decreases with an increase in the size of the passage, and hence the lubricant is separated from the cooling medium. The separated lubricant falls to the space inside the housing, further flows and falls while being supplied to the bearing or the like, and then is accumulated in an oil reservoir between the housing and the rotary scroll. The lubricant that is accumulated in the oil reservoir is pumped toward the cooling medium pump through a shaft passage formed inside the shaft, is used to lubricate each component, and is discharged to the outside along with a liquid cooling medium while being dissolved in the liquid cooling medium.